Re: [PATCH] Add MSI support for SDHCI PCI hosts

[Aaron Lu <aaron.lwe@gmail.com>]

Hello,

On 08/18/2012 01:06 PM, Daniel J Blueman wrote:
> Hi Philip,
> 
> The interrupt could be from another source, though Message Signalled
> Interrupts are a PCI (and variants) only feature at present. I'm happy
> to split the patch and/or make the module param specific to sdhci-pci.

Not sure if you are aware of the following thread:
http://marc.info/?l=linux-mmc&m=133346937412708&w=2

Enabling msi will break some systems.

And more comments below.

> 
> Let's see what the maintainers prefer...Chris?
> 
> Dan
> 
> On 18 August 2012 00:35, Philip Rakity <prakity@marvell.com> wrote:
>>
>> The interrupt source could be from a non-pci device.  Say a gpio or whatever.
>> Does it make sense to break this patch into two patches ?
>>
>> On Aug 17, 2012, at 2:14 AM, Daniel J Blueman <daniel@quora.org> wrote:
>>
>>> Allow module parameter 'enable_msi' to request an MSI interrupt for
>>> hosts where available (presently PCI). Useful as a workaround on
>>> platforms where the legacy interrupt is broken.
>>>
>>> Signed-off-by: Daniel J Blueman <daniel@quora.org>
>>> ---
>>> drivers/mmc/host/sdhci-pci.c |   30 ++++++++++++++++++++++++++++++
>>> drivers/mmc/host/sdhci.c     |   23 +++++++++++++++++++++++
>>> drivers/mmc/host/sdhci.h     |    2 ++
>>> 3 files changed, 55 insertions(+)
>>>
>>> diff --git a/drivers/mmc/host/sdhci-pci.c b/drivers/mmc/host/sdhci-pci.c
>>> index 504da71..fbde589 100644
>>> --- a/drivers/mmc/host/sdhci-pci.c
>>> +++ b/drivers/mmc/host/sdhci-pci.c
>>> @@ -934,6 +934,34 @@ static int sdhci_pci_enable_dma(struct sdhci_host *host)
>>>       return 0;
>>> }
>>>
>>> +static int sdhci_pci_enable_msi(struct sdhci_host *host)
>>> +{
>>> +     struct sdhci_pci_slot *slot;
>>> +     struct pci_dev *pdev;
>>> +     int ret;
>>> +
>>> +     slot = sdhci_priv(host);
>>> +     pdev = slot->chip->pdev;
>>> +
>>> +     ret = pci_enable_msi(pdev);
>>> +     if (ret)
>>> +             return ret;
>>> +
>>> +     host->irq = pdev->irq;
>>> +     return 0;
>>> +}
>>> +
>>> +static void sdhci_pci_disable_msi(struct sdhci_host *host)
>>> +{
>>> +     struct sdhci_pci_slot *slot;
>>> +     struct pci_dev *pdev;
>>> +
>>> +     slot = sdhci_priv(host);
>>> +     pdev = slot->chip->pdev;
>>> +
>>> +     pci_disable_msi(pdev);
>>> +}
>>> +
>>> static int sdhci_pci_8bit_width(struct sdhci_host *host, int width)
>>> {
>>>       u8 ctrl;
>>> @@ -976,6 +1004,8 @@ static void sdhci_pci_hw_reset(struct sdhci_host *host)
>>>
>>> static struct sdhci_ops sdhci_pci_ops = {
>>>       .enable_dma     = sdhci_pci_enable_dma,
>>> +     .enable_msi     = sdhci_pci_enable_msi,
>>> +     .disable_msi    = sdhci_pci_disable_msi,
>>>       .platform_8bit_width    = sdhci_pci_8bit_width,
>>>       .hw_reset               = sdhci_pci_hw_reset,
>>> };
>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>> index 9a11dc3..9fa2180 100644
>>> --- a/drivers/mmc/host/sdhci.c
>>> +++ b/drivers/mmc/host/sdhci.c
>>> @@ -45,6 +45,7 @@
>>>
>>> static unsigned int debug_quirks = 0;
>>> static unsigned int debug_quirks2;
>>> +static bool enable_msi;
>>>
>>> static void sdhci_finish_data(struct sdhci_host *);
>>>
>>> @@ -2433,6 +2434,9 @@ int sdhci_suspend_host(struct sdhci_host *host)
>>>
>>>       free_irq(host->irq, host);
>>>
>>> +     if (host->ops->disable_msi && enable_msi)
>>> +             host->ops->disable_msi(host);
>>> +

Don't know why msi needs to be disabled/enabled on suspend/resume.
And doing this in sdhci_pci_suspend/resume might be more appropriate if
required.

Thanks,
Aaron

>>>       return ret;
>>> }
>>>
>>> @@ -2447,6 +2451,12 @@ int sdhci_resume_host(struct sdhci_host *host)
>>>                       host->ops->enable_dma(host);
>>>       }
>>>
>>> +     if (host->ops->enable_msi && enable_msi) {
>>> +             ret = host->ops->enable_msi(host);
>>> +             if (ret)
>>> +                     return ret;
>>> +     }
>>> +
>>>       ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,
>>>                         mmc_hostname(host->mmc), host);
>>>       if (ret)
>>> @@ -3024,6 +3034,12 @@ int sdhci_add_host(struct sdhci_host *host)
>>>               host->tuning_timer.function = sdhci_tuning_timer;
>>>       }
>>>
>>> +     if (host->ops->enable_msi && enable_msi) {
>>> +             ret = host->ops->enable_msi(host);
>>> +             if (ret)
>>> +                     return ret;
>>> +     }
>>> +
>>>       ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,
>>>               mmc_hostname(mmc), host);
>>>       if (ret) {
>>> @@ -3071,6 +3087,8 @@ int sdhci_add_host(struct sdhci_host *host)
>>> reset:
>>>       sdhci_reset(host, SDHCI_RESET_ALL);
>>>       free_irq(host->irq, host);
>>> +     if (host->ops->disable_msi && enable_msi)
>>> +             host->ops->disable_msi(host);
>>> #endif
>>> untasklet:
>>>       tasklet_kill(&host->card_tasklet);
>>> @@ -3114,6 +3132,9 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
>>>
>>>       free_irq(host->irq, host);
>>>
>>> +     if (host->ops->disable_msi && enable_msi)
>>> +             host->ops->disable_msi(host);
>>> +
>>>       del_timer_sync(&host->timer);
>>>
>>>       tasklet_kill(&host->card_tasklet);
>>> @@ -3162,6 +3183,7 @@ module_exit(sdhci_drv_exit);
>>>
>>> module_param(debug_quirks, uint, 0444);
>>> module_param(debug_quirks2, uint, 0444);
>>> +module_param(enable_msi, bool, 0444);
>>>
>>> MODULE_AUTHOR("Pierre Ossman <pierre@ossman.eu>");
>>> MODULE_DESCRIPTION("Secure Digital Host Controller Interface core driver");
>>> @@ -3169,3 +3191,4 @@ MODULE_LICENSE("GPL");
>>>
>>> MODULE_PARM_DESC(debug_quirks, "Force certain quirks.");
>>> MODULE_PARM_DESC(debug_quirks2, "Force certain other quirks.");
>>> +MODULE_PARM_DESC(debug_quirks2, "Enable MSI interrupt support where possible.");
>>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>>> index 97653ea..df4e003 100644
>>> --- a/drivers/mmc/host/sdhci.h
>>> +++ b/drivers/mmc/host/sdhci.h
>>> @@ -264,6 +264,8 @@ struct sdhci_ops {
>>>       void    (*set_clock)(struct sdhci_host *host, unsigned int clock);
>>>
>>>       int             (*enable_dma)(struct sdhci_host *host);
>>> +     int             (*enable_msi)(struct sdhci_host *host);
>>> +     void            (*disable_msi)(struct sdhci_host *host);
>>>       unsigned int    (*get_max_clock)(struct sdhci_host *host);
>>>       unsigned int    (*get_min_clock)(struct sdhci_host *host);
>>>       unsigned int    (*get_timeout_clock)(struct sdhci_host *host);
>>> --
>>> 1.7.10.4
>>>
>>> --
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>>
> 
> 
>